More than 1000 people who worked on the Galileo program gathered at the laboratory to celebrate the end of the mission.

Emotional celebration

Team member Rosaly Lopes described the farewell celebration as bittersweet.

"It was very emotional. We had people coming here today who worked on Galileo many years ago. Some had retired. Some had left for other jobs and it was like a big family reunion," she said.

"We learned mind-boggling things. This mission was worth its weight in gold"

Claudia Alexander,project manager

At the same time, it was like saying goodbye to an old friend, Lopes said.

Galileo was low on propellant and six years past its original end date. Launched from space shuttle Atlantis in 1989, Galileo travelled about 4.6 billion kilometres (2.8 billion miles) before it disintegrated in Jupiter's dense atmosphere.

Galileo orbited Jupiter 34 times and obtained the first direct measurements of its atmosphere by sending a probe parachuting down toward the planet in 1995.

Underground oceans

It detected evidence of underground salt water oceans beneath the icy crusts of Jupiter's moon Europa. Data also showed that the moons Ganymede and Callisto may have a liquid saltwater layer.

Surface of Jupiter's moon Europafrom images taken by Galileo

Lopes called the Europa finding a major highlight of the mission.

"We had never thought of Europa as a place that could possibly harbour life, so that was a really major discovery," she said.

The spacecraft was purposely put on a collision course with Jupiter.

During the mission, Galileo also examined the lively, intensely hot volcanoes on the moon Io.

Radiation risk

Astronomers hope to retrieve Galileo's data, but radiation from Jupiter could be a problem.

The craft has already weathered more than four times the dose of harmful Jovian radiation it was designed to withstand, and Galileo entered a particularly high-radiation area as it approached the planet.

The spacecraft continued transmitting new information about Jupiter's environment up until the last minute.

"We got the science data until the signal was lost," Lopes said. "It was data about Jupiter's environment fields and particles data."